With the advent of automation in the production environment, the number of products produced in automated factories have increased many fold within the past decade. This has culminated in most manufacturers and system designers feverishly focusing on further improvements in automation to obtain additional advantages in manufacturing efficiency. To be competitive, manufacturers must develop fast and efficient methods for testing the manufactured products.
One method of testing display units currently involves taking a series of pictures of the display unit in different selected display patterns. These pictures, when translated to a digital reference, should corresponds to a predetermined scale of values to ensure that the display unit is functioning properly. However, with this method, the number of required pictures (test screens) are substantial large resulting in a very time consuming period of testing. Additionally, when the contrast levels are near zero-level (e.g., low gray scale), the test unit generates errors because it cannot distinguish between the low gray-scale images and the noise resulting from specks from outside light or the liquid crystal display (LCD) not being flat.
Also, an unreasonable long delay usually results because the camera taking pictures of the display is not synchronized with the display unit displaying the test patterns. Thus, the camera may not be ready to take the picture when the display unit is displaying a test pattern, and vice versa. Any method of manual push-button interaction for controlling the display unit is undesirable, because the resulting contacts to the display may result in movements of the display, and such movements may cause errors.
Thus, what is needed is a synchronized automated method for testing display units that distinguishes between noise and the selected patterns of the display unit quickly and economically.